1. Field of the Invention
This invention relates to an openable motor vehicle roof with a closing element which can be adjusted by a drive in a fixed roof skin for selectively closing or at least partially clearing an opening in the roof, and a process for operating one such motor vehicle roof.
2. Description of the Related Art
A motor vehicle roof of the general type to which the invention is directed is known, for example, from published German Patent Application DE 198 33 811 A1, in which a closing element is provided for a cover of a sliding and lifting roof, the cover element comprising a movable roof headliner. In an area of the front edge of the roof opening is a pressure sensor located roughly in a plane in which the sliding headliner moves, or slightly above it. In this way, the pressure sensor can detect both pinching of an article or body part between the front edge of the cover and the sensor and also between the front edge of the sliding headliner and the sensor. In this way, pinching of an article or body part by the sliding headliner is prevented.
Accomplishing pinch protection for the adjustable cover of an openable motor vehicle roof by way of pinching sensors which are attached to the front edge of the cover or the front edge of the roof opening, and which can be made, for example, as piezoelectric pressure sensors or optical fibers, is generally known, see published German Patent Applications DE 37 31 428 A2 and DE 195 35 796 A1. Since these pressure sensors must be placed over the entire width of the roof opening or of the cover to accomplish effective pinch protection, especially in the form of sensor strips, this pinch protection is very complex. If, on the other hand, for reasons of cost, the number or extension of the sensors is reduced, pinch protection is no longer completely effective.
Furthermore, accomplishing pinch protection for adjustable covers of an openable motor vehicle roof by monitoring the operating parameters of the cover drive motor is known. In this case, the motor current and its change over time, or the torque of the drive motor or its change, and the rpm or rpm change of the motor can be monitored. Examples here are publish German Patent Applications DE 198 40 161 A1; DE 198 40 162 A1; DE 198 40 163 A1; DE 198 40 164 A1; and DE 196 18 219 A1, and German Patents DE 39 29 986 C2, and DE 195 07 541 C1. These processes are also called xe2x80x9cindirectxe2x80x9d processes. The problem with indirect processes is that the generally highly nonlinear kinematics of the cover makes it difficult to detect pinching processes up to the point of impossibility, so that the reliability of these processes is frequently poor, at least under certain operating conditions.
A primary object of this invention is to devise a motor vehicle roof with an adjustable closing element and an adjustable cover element and a process for its operation, with which pinch protection as comprehensive and reliable as possible is obtained in as simple and economical a manner as possible.
This object is achieved in accordance with the invention by a motor vehicle roof with a closing element which is adjustable by a drive for selectively closing or at least partially clearing an opening in a fixed roof skin. The motor vehicle roof includes a cover element located underneath the roof opening and the closing mechanism, the cover element being adjustable by way of a drive in order to conceal or at least partially clear the closing element or the roof opening with respect to the motor vehicle interior. In accordance with the invention, respective drives for the closing element and the cover element are in electronic communication with a controller such that before the start of any movement of the closing element which could result in pinching of body parts or articles between the closing element and an edge of the roof opening edge, the cover element is positioned such that an area of the roof opening which is not covered by the closing element is covered by the cover element at least to a position so that body parts or articles cannot extend into that area which is not covered by the closing mechanism.
This object is also achieved in accordance with the invention by a process for operating an openable motor vehicle roof including steps of providing a closing element which is adjustable by a drive for selectively closing or at least partially clearing an opening in a fixed roof skin, providing a cover element located underneath the roof opening and the closing mechanism, the cover element being adjustable by way of a drive in order to conceal or at least partially clear the closing element or the roof opening with respect to the motor vehicle interior, providing a controller for controller operation of the drives for the closing element and the cover element such that before the start of any movement of the closing element which could result in pinching of body parts or articles between the closing element and an edge of the roof opening edge, the cover element is positioned such that an area of the roof opening which is not covered by the closing element is covered by the cover element at least to a position so that body parts or articles cannot extend into that area which is not covered by the closing mechanism.
In these approaches, it is advantageous that separate pinch protection for the closing element is eliminated since by corresponding control of the cover mechanism, it is always ensured that intentional movement of the closing element cannot lead to pinching of body parts between the closing element and the roof opening edge. The important advantage is that the demands on the closing motion of the closing element are generally very different from the demands on the closing motion of the cover mechanism. For instance, on one hand, for the closing element a much higher closing force is necessary to enable tight closing of the roof opening, while on the other hand, the kinematics of the motion of the closing element generally is much more dramatically nonlinear than the kinematics of the motion of the cover mechanism. As a result of the smaller closing force, under certain circumstances, pinch protection can be abandoned for the cover mechanism. However, if pinch protection for the cover element is necessary, it can be reliably accomplished by way of a so-called indirect process in which, for example, the current of the drive motor or the rpm of the drive motor is monitored. As a result, since the much more dramatically linear kinematics of the motion of the cover mechanism, these processes work reliably here and a complex sensor strip on the cover element or on the edge of the roof opening is not necessary.